DE19734118C1 - Zoom lens arrangement - Google Patents

Abstract

The arrangement includes at least two lenses or lens groups arranged on a common optic axis, which are coupled with piezoelectric or electro-restrictive, linear drives, whereby an active material surface area, undergoing micro-deformation, faces a passive material surface area. At least one of the linear drives comprises two parallel, active material surface areas, between which the passive material surface areas are arranged. The arrangement includes at least two lenses or lens groups arranged on a common optic axis, whose positions are individually or commonly in direction of the optic axis, adjustable in reference to an assembly group connected firmly with an optic instrument. The lenses or lens groups are coupled with piezoelectric or electro-restrictive, linear drives to provide a position change, whereby an active material surface area, undergoing micro-deformation, faces a passive material surface area, and whereby a movement of both material surface areas is triggered with respect to each other. At least one of the linear drives comprises two even, parallel to each other arranged, active material surface areas, whose micro-deformations are directed towards each other, and between which the passive material surface areas are arranged. The active material surface areas are triggered simultaneously, whereby the micro-deformations of both active material surface areas are directed simultaneously towards the passive material surface areas.

Description

The invention relates to a zoom lens with mind arrange at least two on a common optical axis ten lenses or lens groups whose positions (related on a frame connected to an optical device Assembly) individually or together in the direction of the optical Axis are changeable and for the purpose of position changes tion with piezoelectric or electrostrictive linear actuation drives are coupled, in which an active, to microde formations excited material surface of a passive material faces and thus a movement of both Material surfaces is triggered relative to each other.

In classic solutions of the prior art, be knows the relative movement of two lens groups to each other via curves that are assigned to a first lens group, and pegs associated with the second lens group and which are guided in the curves, to steer. There at is the conversion of a uniform rotary Drive movement in a straight-line drive movement with The path-time behavior was transformed. The increasing high demands on the precision resulting from the desired image quality result, have disadvantageously high Manufacturing costs for such fine mechanical components result.

As a result, zoom lenses have recently been developed in which those related to each other and to the Ge Device rack movable optical assemblies on a straight line guides arranged and with piezoelectric linear actuators drives are coupled. Stand with such drives two material surfaces face each other, one of which be  movable, the other is fixed to the frame and from de a surface that can be excited to microdeformations having. These microdeformations are on the opposite standing passive material surface directed and solve a Movement of the two material surfaces relative to each other.

One such is disclosed in U.S. Patent 5,225,941 direction described. Here are two on linear sliding arranged optical assemblies with piezoelectric coupled drives; when controlling these drives there is a linear displacement of the modules against each other at the.

Each of the movable assemblies is a ge dedicated piezoelectric drive. From the An excitation surfaces of the piezoelectric drives Micro movements over rods, which at the same time are the straightforward tion of the optical modules serve to the passive surfaces chen, which are formed on the assemblies, transferred.

There is one transmission link each, which is the microbe transfers to a first assembly, as a straight line tion of the second assembly and vice versa. The means that the straight guide elements with the micro movements are applied. This has the disadvantage that that the modules at least on the guide elements not pick up the micro movement and into a linear motion should change, are not exactly guided.

In addition, it is disadvantageous that the microdeforma tion excited surfaces of the piezoelectric drive do not directly match the passive surfaces to be moved che face, but that intermediate links (namely  the rods of the straight guides) for the transmission of the micro movements on the movable assemblies required are. The disadvantages are not just in the mess accuracy of the guidance of the movable optical assemblies, but also in loss of drives energy due to the relatively long transmission path.

Proceeding from this, the object of the invention is to further develop a zoom lens of the aforementioned type the one that increases guiding accuracy and is effective Transfer of kinetic energy from the active material areas on the passive material surfaces is achieved.

The object of the invention is achieved in that Purpose of changing position at least one as piezoelek tric or electrostrictive linear actuator Positioning drive is provided, in which an active, too Micro-deformation excited material surface of a passive Material surface faces and thereby a movement both material surfaces is triggered relative to each other.

As a major advantage, this eliminates the movement over transfer to the lens groups by converting a rotation movement over curves and cones in a straight line tion, which enables more effective use of the drive sensors is possible and much smaller drive units can be used. The construction of the zoom lens The size becomes simpler and therefore less complex is becoming less. For one or more lenses or Direct movement control is possible for lens groups Lich by specifying an appropriate number of Micro-drive steps the intended change of position  is initiated. This eliminates the disadvantages that stick to the curve.

The proposal according to the invention also has the advantage that with appropriate design each of the be movable lens groups can be controlled separately and so the Changes in position of all driven in this way NEN lens groups are made independently can. This ensures that with the appropriate type control each of the movable lens groups differently can travel distances in the same time units and desired position corrections while moving are executable.

The structure of piezoelectric and / or electrostrictive Stepper motors for this purpose is manufacturing technology easy to do. For the stimulable active material For example, polycrystalline piezoelectric surfaces can be used tric ceramics that are in the micro shock drive technology have already proven to be used.

An advantageous embodiment of the invention is in that the piezoelectric or electrostrictive linea drive several active material surfaces, so-called Resona has gates with a lens or lens group me are firmly connected in the meantime, while the respective ge opposing passive material surfaces are arranged. The device-fixed arrangement of passive materials alflächen offers the advantage that these in their dimensions can be expanded to include several active Ma material surfaces can face the different Lenses or lens groups are assigned, whereby the pas sive material surfaces are part of several linear motors. So  it is conceivable, for example, a passive material surface to be arranged parallel to the optical axis and over the ver to expand the range of all lens groups, weh rend the individual movable lens groups with separate active material surfaces are provided, each single Lich in one area against this common passive Work material surface, but can be controlled separately.

A particularly advantageous embodiment of the invention stipulates that for each linear drive two are trained Dete active material areas provided and approximately parallel are arranged to each other, the microdeformations of these two active material surfaces approximately towards one another are directed and between the two active material surfaces opposing passive material surfaces are provided. It should also be provided that the active material surfaces are excited at the same time and there due to the microdeformations on both active material surfaces at the same time on the opposing liabilities Material surfaces are directed. It is thus achieved that the pressure and tensile forces caused by the microdeformations not from the bearings and guide elements of the be appropriate lens group must be included.

To achieve a reversal of direction of the linear movement can can be provided, for example, that each active material area che or each resonator a full-surface electrode and has an electrode divided into a 2 × 2 matrix. Become this is diagonally electrically connected to each other and is on one of these resulting electrode pairs as well a common back electrode an alternating electrical field applied, the resonator moves in two vibrations fashion, are oriented perpendicular to each other. From this resul  an elliptical movement of the resonator that over the tappet movements or microdeformations the opposite passive material surface is created and there caused the desired relative movement. To Rich the other pair of electrodes is turned on controls.

A preferred embodiment is within the scope of the invention tion variant in which it is provided that two lenses or Lens groups are present, each lens or lens group a separate linear actuator is assigned and both Li near drives in different, orthogonal to each other NEN, the optical axis of the zoom lens as a cut have just arranged.

This makes it possible for all functionally essential assemblies (Lens groups, drives) in the smallest possible space under bring and still the clarity of the arrangement and thus the accessibility of the individual assemblies achieve.

A configuration in which all is also advantageous Lin coupled with one of the aforementioned linear drives sen or lens groups on separate straight guides are. This is the independence of the lens groups in terms of their leadership, ensuring everyone Lens group one in terms of size and accuracy fit straight line can be assigned. So it is possible Lich, different peculiarities of individual lens groups to be considered and, for example, the powerful speed of the linear drive exactly the mass of the lens group adapt.  

In this context, further training is conceivable Invention in which the passive material surfaces of one or several linear drives as elements of straight-line guidance for one or more lenses or lens groups are formed. This results in an additional burst savings in the construction of the zoom lens.

In a particularly preferred embodiment of the invention it is envisaged that each existing linear drive via egg ne control circuit linked to a program unit is in the position target data and / or motion sequence Data saved for the assigned lens or lens group are chert.

This ensures that each linear actuator is dependent of which movement or position changes the lens group assigned to him can be controlled is. The retrieval of ge in a common program unit stored default data for the movements or Po Change of position of the individual lens groups can with Hil fe of a software program adapted to the zoom lens respectively.

Another embodiment of the invention provides that at least one of the lenses or lens groups a positive assigned to the detection of actual position data and the signal output of the position detector with the control switching the verbun with this lens or lens group to which linear drive is linked the control circuit in this case has a comparator for comparison the actual position data with the target position data and via a calculation circuit for determining correction values  from the deviations of the actual position data from the Po sition target data.

This ensures high reproducibility in the positioning guaranteed the individual lens groups. Is with for example, the predefined with the stored data The end of the movement is done with the help of the position indicator a control is possible whether the ingested ne position of the specified or desired positions actually corresponds or due to any influences the target positions have not been reached. Results this control is a deviation, the linear actuator put back into operation and the movement of the lens group by a path determined from the deviation from target to actual prompted. At the end of this sequence of movements again using the position indicator the actual position averaged and compared to the corrected target position data chen. This process repeats itself until the Arithmetic circuit no longer deviates between the actual position tion and the corrected target position determined.

In this context it can further be provided that a periodic correction of the ge in the program unit stored target position data and / or motion sequence Data depending on the actually reached position of the lens groups and / or the image obtained goodness is done.

In this respect, it is advantageous if in the control circuit a calculation circuit for determining correction values the assessment of those achieved with the actual position data Image quality is provided. This can be done, for example, by Aus  evaluation of the image brightness, the image contrast and / or the Sharpness is done.

The invention is described below with reference to an embodiment game are explained in more detail. In the associated drawing shows:

Fig. 1 pen shows a longitudinal section through an inventive zoom lens with two movable lens groups

FIG. 2 shows a section AA through the zoom lens from FIG. 1

Fig. 3 is a block diagram for controlling the linear drives assigned to the lens groups

In Fig. 1, a zoom lens is shown, in which a first lens group 1 and a second lens group 2 in the direction of a common optical axis are arranged displaceably. 3 The first lens group 1 is fixed in a sliding body 4 , the second lens group 2 in a sliding body 5 and aligned in this to the optical axis. The sliding body 4 with the first lens group 1 is on a guideway 6 , the sliding body 5 with the second lens group 2 is slidably mounted on a guideway 7 . The guide tracks 6 and 7 are aligned parallel to the optical axis, as a result of which the lens groups 1 , 2 can be displaced in the direction of the optical axis 3 .

The guideways 6 , 7 are on a device part 8 BEFE Stigt. Also attached to the device part 8 is an optical module 9 , which is part of the zoom lens or an optical device and which cooperates with the two lens groups 1 and 2 during image generation.

The displaceability of the lens groups 1 and 2 on the optical axis 3 ensures a change in position of both lens groups relative to the optical assembly 9 and thus the change in distance a as well as a change in position of the two lens groups 1 relative to one another or the change in distance b. With a position change of lens groups 1 and 2 , the focus of the zoom lens should be on a focal point, while the change in the distance between the two lens groups changes the focal length of the zoom lens.

In order to maintain the image quality during the adjustment of the focal length, it is necessary that the lens groups 1 and 2 can move at different speeds. High-precision positioning is also necessary.

In order to be able to make the changes to the setting of the zoom lens exactly in the manner described, both the lens groups 1 and the lens group 2 are each coupled to a piezoelectric linear drive 10 , 22 ; the two piezoelectric linear drives 10 , 22 can be controlled separately (cf. FIGS. 2 and 3).

In Fig. 2 the zoom lens in a section AA from Fig. 1 can be seen, with a schematic representation of the side view of a piezoelectric linear actuator 10 which is mechanically connected to the sliding body 5 and above this with the lens group 2 . The piezoelectric Li nearantrieb 10 has a drive element 14 on two active material surfaces 11 and 12 , which are arranged parallel to each other. The active material surfaces 11 and 12 are resonators made of piezoceramic material, which can be excited to ram movements or microdeformations on its surface. The active material surfaces 11 and 12 or the resonators are directed towards one another with regard to the alignment of the tappet movements. Due to the tappet movements surface parts of the active material surfaces 11 , 12 periodically reach the surface of a rule between the two active material surfaces 11 and 12 angeord Neten rod 13 , which form the passive material surfaces of the linear actuator 10 . In this way, one of the active material surfaces 11 or 12 faces a passive material surface.

If the active material surfaces 11 , 12 are excited, this leads to micro-shock movements, as a result of which a movement of the active material surfaces 11 , 12 relative to the passive material surface is triggered.

As a result, the drive element 14 executes a movement relative to the rod 13 , which is transmitted to the sliding body 5 and from there to the lens group 2 . The direction of movement of the sliding body 5 is given by the micro-impacts, with a straight line through the guideways 6 and 7 . The direction of the movement is reversed by correspondingly controlling the active material surfaces 11 , 12.

To achieve the reversal of direction can be seen as an example that each active material surface 11 and 12 or each resonator has a full-surface electrode and an electrode divided into a 2 × 2 matrix. These electrodes are electrically connected to each other diagonally. If an alternating electric field, the frequency of which corresponds to the resonance frequency of the resonator, is applied to a common back electrode and one of the diagonally connected electrode pairs, the resonator moves in two mutually perpendicular vibration modes; the superimposition of these movements results in an elliptical movement of the resonator, which generate force effects against the rod 13 via the plunger or microdeformations and thereby cause the relative movement. The other pair of electrodes is controlled to reverse the direction.

In Fig. 2 it can also be seen that the sliding body 5 has a guide 15 closed around the guide track 7 and a guide 16 open around the guide track 6 . The sliding body 5 is fixed in all directions perpendicular to the direction of the device. This results in a low-friction and precise guidance of the sliding body 5 in the direction of the optical axis 3 .

The piezoelectric linear drive 10 is, as shown in the drawing, arranged in the plane in which the Mittenach se 17 lies. Analogously, a second piezoelectric linear drive 22 , not shown in FIG. 2 for the sake of clarity, is coupled via the sliding body 4 and with the lens group 1 , which lies in a plane rotated by 90 ° about the optical axis, ie in one Level with the central axis 18 is arranged.

By way of example, the second piezoelectric linear drive 22 can also be arranged in the same plane as the linear drive 10 , aligned with this, which results in the possibility of using the same passive material surfaces of the rod 13 for both linear drives 10 , 22 . There is only the difference with regard to the mechanical coupling to the sliding bodies or to the lens groups; while the piezoelectric linear drive 10 is coupled to the lens group 2 via the sliding body 5 , the piezoelectric linear drive 22 is connected to the lens group 1 via the sliding body 4 .

In Fig. 3, a position detector 19 is shown, the actual data for detecting the position of the two lenses groups 1 and 2 with reference to markings 20/21, which are attached to the lens groups 1 and 2, is provided. The position detector 19 can be designed, for example, as an optoelectronic incremental encoder.

In the block diagram of FIG. 3, a program unit 23 is provided which is connected to one of its signal outputs via a control circuit 24 on the piezoelectric linear drive 10 , while a second signal output is connected via a control circuit 25 to the second piezoelectric linear drive 22 . The target position data and / or the movement sequence data for the lens groups 1 , 2 are stored in the program unit 23 . The stored data are assigned to certain focal lengths of the zoom lens.

Corresponding to an instruction entered manually or otherwise via input 26 , for example by software control, the program unit 23 issues control commands to one or both of the control circuits 24 and 25 which correspond to the desired position data and from there to the piezoelectric linear drives 10 and / or 22 are passed on.

These control commands can be specified in the form of a number of pulses with which the respective active material surface of the piezoelectric linear drive 10 and / or 22 in question is excited, whereby a number corresponding to this pulse number will cause micro-deformations, in the manner already described are converted into a relative movement between the active material surface and the passive material surface and thus cause a change in position of the lens group in question, in which the number of pulses is equivalent to the path length.

In order to be able to compensate for inaccuracies in the result of this actuating movement, the actual position data captured by the position detector 19 are applied to a second input of each control circuit 24 and 25 . A comparator is provided within each control circuit 24 , 25 , which compares the actual position data with the desired position data.

The output of the comparator is connected in both control circuits 24 , 25 to a computing circuit 29 and 30 , which takes into account the deviations of the actual position data from the target position data and gains correction values therefrom, which, for the purpose of readjustment, the respective piezoelectric linear drive 10 and / or 22 are supplied.

This ensures a high degree of reproducibility of positions of lens groups 1 and 2 . In addition, it is conceivable to periodically correct the target position data and / or movement sequence data stored in the program unit 23 as a function of the image quality achieved in each case in order to ensure high image quality.

Analogous to the application of the actual position data from the position detector 19 to the second inputs of the control circuits 24 and 25 , it is conceivable to place information from the assessment of the image quality achieved with the actual position data and this information in a manner similar to that in FIG the manner described with the aid of a suitable arithmetic circuit, which is to be integrated into each of the control circuits 24 and 25 , for determining readjustment commands for the piezoelectric linear drives 10 and / or 11 .

Reference list

1

first lens group

2nd

second lens group

3rd

optical axis

4th

,

5

Sliding body

6

,

7

Guideways

8th

Device part

9

optical assembly

10th

piezoelectric linear actuator

11

,

12th

active material areas

13

Rod

14

Drive element

15

closed tour

16

open leadership

17th

,

18th

Center axes

19th

Position detector

20th

,

21

Markings

22

piezoelectric linear actuator

23

Program unit

24th

,

25th

Control circuits

26

entrance

27

,

28

Comparator

29

,

30th

Arithmetic circuit
a, b distances

Claims (8)

1. Zoom lens with at least two lenses or lens groups arranged on a common optical axis, the positions of which, based on a module permanently connected to an optical device, can be changed individually or jointly in the direction of the optical axis and for the purpose of changing the position are coupled with piezoelectric or electrostrictive linear drives, in which an active, micro-deformation excited material surface is opposed to a passive material surface and thereby a movement of both material surfaces is triggered relative to each other, characterized in that at least one of the linear drives has two planes, essentially parallel to one another aligned active material surfaces ( 11 , 12 ), whose renal deformations are essentially directed towards one another and between which the passive material surfaces are arranged, the active material surfaces ( 11 , 12 ) being simultaneously excited and thereby di e Micro-deformations of both active material surfaces ( 11 , 12 ) are simultaneously directed onto the passive material surfaces. 2. Zoom lens according to claim 1, characterized in that for each lens or group of lenses ( 1 , 2 ) is a Geson changed straight line is provided. 3. Zoom lens according to one of the preceding claims, characterized in that the passive material surfaces are simultaneously designed as elements of the linear guidance for one or more lenses or lens groups ( 1 , 2 ). 4. Zoom lens according to one of the preceding claims, characterized in that two lenses or lens groups ( 1 , 2 ) are provided and each separately with egg nem piezoelectric or electrostrictive linear actuator are coupled, the elements of the Gerad leadership tion of both lenses or lens groups ( 1 , 2 ) separated, in the optical axis ( 3 ) intersecting and orthogonally aligned planes are assigned, whereby a shift of the lenses or lens groups ( 1 , 2 ) perpendicular to the optical axis ( 3 ) is excluded. 5. Zoom lens with at least one linear drive according to one of the preceding claims, characterized in that each linear drive provided is linked via a control circuit ( 24 , 25 ) to a program unit ( 23 ), in the position target data and / or loading Motion sequence data for the assigned lens or lens group ( 1 , 2 ) are stored. 6. Zoom lens according to claim 5, characterized in that the lens or lens group ( 1 , 2 ) is assigned a position detector ( 19 , 22 ) for detecting actual position data and the signal output of the position detector ( 19 , 22 ) with the control circuit ( 24 , 25 ) of the linear drive ( 10 , 22 ) is linked, the control circuit ( 24 , 25 ) via a comparator ( 27 , 28 ) for comparing the actual position data with the desired position data and via a computing circuit ( 29 , 30 ) for determining correction values from the deviations of the actual position data from the desired position data. 7. Zoom lens according to claim 5 or 6, characterized in that a periodic correction of the desired position data and / or movement sequence data stored in the program unit ( 23 ) is provided as a function of the image quality achieved in each case. 8. Zoom lens according to one of claims 5 to 7, characterized characterized in that a Re circuit for determining correction values the assessment of the achieved with the actual position data th image quality is provided.